Scientists paint a more nuanced picture of the gorilla genome

Susie, a female Western lowland gorilla, was used as the reference sample for full-genome sequencing and assembly. This material relates to a paper that appeared in the April 1, 2016, issue of Science, published by AAAS. The paper, by D. Gordon at University of Washington School of Medicine in Seattle, Wash., and colleagues was titled, 'Long-read sequence assembly of the gorilla genome.'

Using high-tech sequencing techniques, geneticists at the University of Washington’s Eichler lab have produced a near-complete gorilla genome. Their research, which could yield important biological information about apes and humans alike, was published Thursday in the journal Science.

The Western lowland gorilla genome was first sequenced in 2012. But that construction, known as the GorGor3 genome, contained more than 400,000 gaps. By using a technique called long-read sequencing technology, researchers at the Eichler lab were able to close more than 90 percent of those gaps.

“One of the goals of the Eichler lab is to create a comprehensive catalogue of known genetic differences between humans and other great apes,” says Christopher Hill, who co-authored the study. “The differences between species may aid researchers in identifying regions of the human genome that are associated with cognition, behavior, and neurological diseases. Having complete and accurate reference genomes to compare allows researchers to uncover these differences.”

Hill and colleagues based their research on Susie, a gorilla at the Lincoln Park Zoo in Chicago. The new genome, dubbed Susie3, has already provided some surprising insight into the evolutionary history of lowland gorillas.

“The new gorilla genome assembly provides us with a slightly different picture of the evolutionary history of the Western lowland gorilla,” says Dr. Hill, who is a senior fellow at the Eichler lab. “Prior studies have shown that the gorilla population underwent a bottleneck 50,000 years ago, but analyses on the new genome shows that the bottleneck was more severe than we previously thought. Furthermore, patterns of genetic variation within the gorilla genome can provide evidence of how disease, climate change, and human activity affect lowland gorilla populations.”

The Eichler lab’s sequencing process may afford more accurate sequencing of other mammalian genomes. Researchers are already moving to complete the genomes of the other members of the great ape family, which encompasses gorillas, chimpanzees, orangutans, and humans. Such advances could provide a foundation for future breakthroughs on the genetics of primate cognition and behavior.

“The bigger surprise came once we started drilling down at the differences between the previous and new gorilla genomes,” Hill says. “We are finding a large number of novel structural variants in coding regions of the gorilla genome that have not been seen before. I’m sure the biggest surprise will be what other researchers are able to uncover with this new reference genome.”